In order to obtain an accurately converged solution in a minimal amount of time, the porous medium
model is used to replace a complicated 3D model to analyze flow field of gas duct, the results show that the
height of discharge region, the expansion angle and the width of discharge region could affect the flow in the
gas duct of CO2 laser with pin-to-plate discharge. As the appropriate selection, the height of discharge region
is 43.5 mm and the expansion angle is 8-10 degree, also, the length of gas duct is slightly larger (20-30 mm)
than the width of the anode plate. The flow of the discharge region and stress on the cathode pin are influenced
by arrangement of cathode pin, it concludes that the clutter arrangement is much better than the regular
arrangement.